In some hydraulic circuits it is desired to temporarily connect pressure or test circuits to the hydraulic system for leak checking, pressure checks, or other test purposes. For instance, some aircraft hydraulic circuits require ground support pressure checks, and access fitting manifolds are used for such purpose.
With some circuits utilizing a pump, the attachment to the access fitting of a pressurized test conduit has a detrimental effect on the pump, such as producing "motoring" of the pump. In such instance, it is necessary to temporarily exclude the pump from the hydraulic circuit being tested, and while check valves have been used for this purpose they are often unsatisfactory because of the occurrence of cavitation during normal circuit use.
It is an object of the invention to provide an access fitting and valve for a hydraulic manifold wherein operation of the access valve produces an automatic control of the flow path of the manifold.
A further object of the invention is to provide an access fitting for a hydraulic manifold wherein connection of a conduit to the access fitting displaces a valve element which seals portions of the manifold hydraulic circuit, and permits other portions of the hydraulic circuit to communicate with the conduit attached to the access fitting.
An additional object of the invention is to provide a hydraulic manifold with an automatic flow control access fitting wherein the access fitting components may be installed and removed as a cartridge assembly for simplifying maintenance and assembly.
In the practice of the invention a hydraulic circuit includes a manifold having a flow passage defined therein and an access fitting is incorporated into the manifold body for selective attachment of a pressure check conduit thereto.
The access fitting includes a passage which intersects the manifold's flow passage at right angles and a valve element is displaceable within the fitting passage between a blocking position which seals the manifold flow passage, and an open position which permits fluid flow through the manifold flow passage and seals the access fitting passage. Attachment of a conduit to the access fitting automatically displaces the valve element between its two positions, and movement of the valve element to seal the access fitting upon removal of the test conduit is augmented by a compression spring.
The valve element includes a bypass passage, and key structure is utilized with the valve causing the valve to rotate about its axis through 90.degree. as the valve element is displaced from its access fitting sealing position to its manifold flow passage blocking position. When in the blocking position the bypass passage communicates with a selective portion of the hydraulic circuit flow passage.
The structure of the access fitting, including the valve element, are assembled within a cartridge and the apparatus of the invention may be quickly removed or installed into the manifold body.